tuber

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A swollen, fleshy, usually underground stem of a plant, such as the potato, bearing buds from which new plant shoots arise.
2. n. A rounded projection or swelling; a tubercle.

Century Dictionary and Cyclopedia

1. n. In botany, a subterranean body, usually of an oblong or rounded form, consisting morphologically of a stolon-like branch of a rhizome, much thickened, commonly at the end, and beset with “eyes,” which are properly modified axillary buds. Some of these buds normally sprout the second season, giving rise to a new plant, for the nourishment of which the tuber is richly stored with starch. Typical examples are the common potato and the Jerusalem artichoke (see Helianthus, with cut); less familiar are the tubers of the dwarf dandelion (Krigia Dandelion), the American ground-nut (Apios tuberosa) and the ground-nut of Great Britain, Conopodium denudatum (Bunium flexuosum). Moniliform tubers occur, as in Equisetum fluviatile (see moniliform) and Hydrocotyle Americana (see Hydrocotyle). Strictly, the tuber is to be distinguished from the tubercle (see tubercle ) and the tuberous root (see tuberous); but the term often embraces these, especially the former.
2. n. A genus of subterranean discomycetous fungi, the truffles, having the peridium warty or tubercled, without definite base, the asci ovoid or globose, and one- to three- or (rarely) four-spored. About 50 species are known. T. æstivum is the common truffle. See truffle (with cut).
3. n. In pathol., anat., and zoology, some rounded swelling part; a tuberosity; a tubercle; a knot or swelling which is not the result of disease: used chiefly as a Latin word (with Latin plural tubera).

Wiktionary

1. n. A fleshy, thickened underground stem of a plant, usually containing stored starch, as for example a potato or arrowroot.
2. n. horticulture A thickened "root-stock".

GNU Webster's 1913

1. n. A fleshy, rounded stem or root, usually containing starchy matter, as the potato or arrowroot; a thickened root-stock. See Illust. of tuberous.
2. n. A genus of fungi. See truffle.
3. n. (Anat.) A tuberosity; a tubercle.

WordNet 3.0

1. n. a fleshy underground stem or root serving for reproductive and food storage
2. n. type genus of the Tuberaceae: fungi whose fruiting bodies are typically truffles